Evidence from land and census records, and the Book of Recorded Marks and Brands prove that Alexander came to Utah in 1849. He filed for a lot in Salt Lake City in 1849, and sold land in Salt Lake City 30 September 1852.
He appears on the 1850 Utah census with his mother, Mary Noble Gardner. On 23 May 1850 he registered the brand for his cattle (AG on the left hip). This occured before the arrival of any pioneer company in 1850.
His mother traveled to Utah with the 1849 Allen Taylor Company, but Alexander's name does not appear on the hand-written roster. Further research is needed to determine the name of the pioneer company he traveled with.
His death date is confirmed by the Deseret News article telling of his suicide in Nephi, Utah.